Improvement in automatic brakes for elevators



H. PEARCE;

Automatic Brake for Elevator.

PatentedlSQpl! Z,..., 1.8 75.

FIG-l.

] Aifiy Il H UNITED STATES HENRY PEARCE, OF CINCINNATI, OHIO.

IMPROVEMENT IN AUTOMATIC BRAKES FORELEVATORS.

Specification forming part of Letters Patent No. 1 67,560, datedSeptember 7, 1875 application filed August 17, 1675.

To all whom it may concern Be it known that I, HENRY PEARCE, ofCincinnati, Hamilton county, Ohio, have invented a new and usefulAutomatic Brake for Elevators, of which the following is aspecification:

This invention, while applicable to every kind of elevator-platform, ismore especially designed for those which are operated by ahoisting-cable, and is intended to prevent the fall of the platform inthe event of the giving way of the cable from any cause.

The ordinary safety devices depend on the working parts going intoprompt operation the moment the platform begins to fall, while minekeeps hold and only lets go as the platform travels up or down in itscustomary work, so that the safety device is in a condition of visibleand constant efficiency.

My invention consists essentially of an escapement latch or palletpivoted to the platform and weighted on one side, and of two.

racks made fast in the hatchway, of which one coacts with such sideweight to vibrate said escapement-latch, and to cause it to promptlyengage with the other rack in the event of a sudden descent of theplatform, as hereinafter explained.

In the accompanying drawing, Figure 1 is a perspective view,representing a platform and portion of a hatchway provided with myimprovement. Figs. 2, 3, 4, and 5 are side elevations, showin gm yescapement-latch in different positions upon the rack. Fig. 6 representsa modification of my overpoise.

The following parts may be of customary or any approved form, to wit:Stanchions A A, the cage or platform B, and the hoisting and suspendingcable 0. These members require, therefore, no specific description. Toeither or both of the stanchions I attach one or more peculiarly-formedduplex racks. Each of said duplex racksconsists of a series ofequidistant upturned ratchet-teeth, D, with interposed depressions E.The other member of said duplex rack consists of a series of obtuseserrations or undulations, F, whose consecutive distances are preciselyequal to those of the ratchet D.

The illustration shows one of such duplex racks attached to eachstanchion; but it is evident that each stanchion may have such a duplexrack on its rear as Well as on its front side, and the ratchet-teeth ofone rack may either as in the present illustrationoccupy correspondinglevels with those on the other duplex rack, and consequently becomeeffective simultaneously therewith, or the teeth of the respectiveduplex racks may be set at slightly-different elevations, so as toreduce the distance of platform fall before its arrest by the brakeaction.

Gr is my pallet or escapement-latch, the same consisting of a steel orwrought-iron bar, havin g a hooked upper extremity, H, which hookprojects in the plane of said bars vibration about a horizontal pivot,I, by which said latch is secured to the side of the cage or platform.The pivot I is located near the midlength of said bar, but sufficientlyto one side of its center of gravity to secure a preponderating weightor overpoise for the front edge of said bar, sufficient to cause thehooked upper end H to tend to retire from and pass without contact overthe ratchet-teeth D during the normal action of the platform. A Wrist,J, which extends laterally from the lower end of the escapement, carriesa roller, K, which, during the normal action of the hoist, rests uponthe undulating edge of the member F. Said roller, or, at least, itsperiphery, may be composed of indiarubher or other elastic material.

In order to insure the proper overpoise of the latch G there may be aprojection, L, from its front edge. This projection may take the form ofa bar, as at L, Fig. 6, and the weight proper l be secured thereto by ascrew, M, or other means, so as to be adjusted at will.

The undulating member F might be dispensed with, and the roller K beoperated by contact with the ratchet D.

That portion of the hook H which in the breaking action comes in contactwith the ratchet D may be shod orplugged with lead or other materialsofter than that of which the bar proper is composed, in order to easethe percussion incident to sudden contact.

1 have shown my safety device in its application to prevent a suddendescent of the platform; but it may manifestly be made available toprevent a too rapid ascent of a counevent of accident.

terbalanced platform by a simple reversion of the parts.

The operation of my brake is as follows: So long as the platform isascending or descending in the usual way the overpoise of theescapement, by pressing the roller K into the Y depressions of thenn'dulation F, causes the hook H to pass without touching the ratchet D.The moment, however, that the platform breaks loose from its cable, theplatform and the overpoise descend with equal rapidity, so as toneutralize or destroy, for the time being, the relative gravity of theoverpoise, and consequently the hook H retains the rearward position, towhich the last effective prominence of the undulation F has forced it,(see Fig. 4,) and by the'descent of the platform becomes interlockedwith the nearest ratchet-tooth, as in Fig. 5. i

This safety device, being continually in motion during the normaloperation of the hoist, gives assurance of its instant efliciency in theThe constant clearance of the escapement during normal action of theplatform is attributable to the weighted side of the latch being free todrop more quickly than the more slowly-descending suspended platform. Onthe contrary, the instant that the platform breaks loose from its cable,it is, of course, at liberty to descend as quickly as any part of theescapement, whose relative gravity, being thus neutralized, is no longereffective to draw the hook clear of the ratchet, and these members, theninterlocking, effectually arrest the platform.

I claim as new and of my invention 1. The combination of duplex rack DF, attached to the hatchway, and escapement-latch or pallet G, pivotedeccentrically to the hoist, or their equivalents, substantially as setforth.

2. In combination with duplex rack D F, or its equivalent, theoverpoised latch or pallet G H I J In'testimony of which invention Ihereunto set my hand.

' HENRY PEARCE.

Attest:

GEO. H. KNIGHT, WALTER KNIGHT.

